Photocatalyzed degradation of lignin on TiO2

In lignin solution with suspended TiO2 lignin adsorbed to TiO2. The illumin ation of the suspension by UV (lambda > 310 nm) brought about the desorptio n as well as the degradation of lignin. The tight adsorption was suggested by the suppression of CO2 evolution, which accompanies the degradation, at high concentration of lignin. During the degradation the aromatic moiety wa s transformed faster than the aliphatic side chain. In the transformation p rocess lignin was polymerized in the beginning and then converted to smalle r molecule successively. Oxygenated compounds such as carboxylate and aldeh yde were formed as intermediates. (C) 1999 Elsevier Science B.V. All rights reserved.